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  1. Article ; Online: Laminar Excitatory Inputs to the Dorsolateral Prefrontal Cortex: Implications for Periadolescent Synaptic Plasticity and Circuit Pathology.

    Medalla, Maria / Zikopoulos, Basilis

    Biological psychiatry

    2023  Volume 94, Issue 4, Page(s) 280–282

    MeSH term(s) Dorsolateral Prefrontal Cortex ; Synaptic Transmission ; Neurons ; Neuronal Plasticity ; Prefrontal Cortex
    Language English
    Publishing date 2023-07-26
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Comment
    ZDB-ID 209434-4
    ISSN 1873-2402 ; 0006-3223
    ISSN (online) 1873-2402
    ISSN 0006-3223
    DOI 10.1016/j.biopsych.2023.06.005
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Cologne/Königswinter

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  2. Article ; Online: The highways and byways of the brain.

    Hilgetag, Claus C / Zikopoulos, Basilis

    PLoS biology

    2022  Volume 20, Issue 3, Page(s) e3001612

    Abstract: Brain functions rely on the communication network formed by axonal fibers. However, the number of axons connecting different brain regions is unknown. A study in PLoS Biology addresses this question and finds that most areas of the human cerebral cortex ... ...

    Abstract Brain functions rely on the communication network formed by axonal fibers. However, the number of axons connecting different brain regions is unknown. A study in PLoS Biology addresses this question and finds that most areas of the human cerebral cortex are linked by an astoundingly small number of fibers.
    MeSH term(s) Axons ; Brain ; Cerebral Cortex ; Humans
    Language English
    Publishing date 2022-03-31
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, N.I.H., Extramural ; Comment
    ZDB-ID 2126776-5
    ISSN 1545-7885 ; 1544-9173
    ISSN (online) 1545-7885
    ISSN 1544-9173
    DOI 10.1371/journal.pbio.3001612
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    Zs.A 6193: Show issues Location:
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  3. Article: Editorial: Methods and applications in frontiers in neuroanatomy.

    Ricard, Clément / Alonso-Nanclares, Lidia / Zikopoulos, Basilis / Oheim, Martin

    Frontiers in neuroanatomy

    2023  Volume 17, Page(s) 1256867

    Language English
    Publishing date 2023-08-29
    Publishing country Switzerland
    Document type Editorial
    ZDB-ID 2452969-2
    ISSN 1662-5129
    ISSN 1662-5129
    DOI 10.3389/fnana.2023.1256867
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  4. Article ; Online: The highways and byways of the brain.

    Claus C Hilgetag / Basilis Zikopoulos

    PLoS Biology, Vol 20, Iss 3, p e

    2022  Volume 3001612

    Abstract: Brain functions rely on the communication network formed by axonal fibers. However, the number of axons connecting different brain regions is unknown. A study in PLoS Biology addresses this question and finds that most areas of the human cerebral cortex ... ...

    Abstract Brain functions rely on the communication network formed by axonal fibers. However, the number of axons connecting different brain regions is unknown. A study in PLoS Biology addresses this question and finds that most areas of the human cerebral cortex are linked by an astoundingly small number of fibers.
    Keywords Biology (General) ; QH301-705.5
    Language English
    Publishing date 2022-03-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Article: A neural model of modified excitation/inhibition and feedback levels in schizophrenia.

    Zhu, Jiating / Zikopoulos, Basilis / Yazdanbakhsh, Arash

    bioRxiv : the preprint server for biology

    2023  

    Abstract: The strength of certain visual illusions is weakened in individuals with schizophrenia. Such phenomena have been interpreted as the impaired integration of inhibitory and excitatory neural responses, and impaired top-down feedback mechanisms. To ... ...

    Abstract The strength of certain visual illusions is weakened in individuals with schizophrenia. Such phenomena have been interpreted as the impaired integration of inhibitory and excitatory neural responses, and impaired top-down feedback mechanisms. To investigate whether and how these factors influence the perceived illusions in individuals with schizophrenia, we propose a two-layer network that can model visual receptive fields (RFs), their inhibitory and excitatory subfields, and the top-down feedback. Our neural model suggests that illusion perception changes in individuals with schizophrenia can be influenced by altered top-down mechanisms and the organization of the on-center off-surround receptive fields. Alteration of the RF inhibitory surround and/or the excitatory center can replicate the difference of illusion precepts between individuals with schizophrenia and normal controls. The results show that the simulated top-down feedback modulation enlarges the difference of the model illusion representations, replicating the difference between the two groups. We propose that the heterogeneity of visual and in general sensory processing in schizophrenia can be largely explained by the degree of top-down feedback reduction, emphasizing the critical role of top-down feedback in illusion perception, and to a lesser extent on the imbalance of excitation/inhibition. Our neural model provides a mechanistic explanation for the modulated visual percepts in schizophrenia with findings that can explain a broad range of visual perceptual observations in previous studies. The two-layer motif of the current model provides a general framework that can be tailored to investigate subcortico-cortical (such as thalamocortical) and cortico-cortical networks, bridging neurobiological changes in schizophrenia and perceptual processing.
    Language English
    Publishing date 2023-04-28
    Publishing country United States
    Document type Preprint
    DOI 10.1101/2023.04.24.538166
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article: A neural modeling approach to study mechanisms underlying the heterogeneity of visual spatial frequency sensitivity in schizophrenia.

    Dugan, Caroline / Zikopoulos, Basilis / Yazdanbakhsh, Arash

    bioRxiv : the preprint server for biology

    2023  

    Abstract: Patients with schizophrenia exhibit abnormalities in spatial frequency sensitivity, and it is believed that these abnormalities indicate more widespread dysfunction and dysregulation of bottom-up processing. The early visual system, including the first- ... ...

    Abstract Patients with schizophrenia exhibit abnormalities in spatial frequency sensitivity, and it is believed that these abnormalities indicate more widespread dysfunction and dysregulation of bottom-up processing. The early visual system, including the first-order Lateral Geniculate Nucleus of the thalamus (LGN) and the primary visual cortex (V1), are key contributors to spatial frequency sensitivity. Medicated and unmedicated patients with schizophrenia exhibit contrasting changes in spatial frequency sensitivity, thus making it a useful probe for examining potential effects of the disorder and antipsychotic medications in neural processing. We constructed a parameterized, rate-based neural model of on-center/off-surround neurons in the early visual system to investigate the impacts of changes to the excitatory and inhibitory receptive field subfields. By incorporating changes in both the excitatory and inhibitory subfields that are associated with pathophysiological findings in schizophrenia, the model successfully replicated perceptual data from behavioral/functional studies involving medicated and unmedicated patients. Among several plausible mechanisms, our results highlight the dampening of excitation and/or increase in the spread and strength of the inhibitory subfield in medicated patients and the contrasting decreased spread and strength of inhibition in unmedicated patients. Given that the model was successful at replicating results from perceptual data under a variety of conditions, these elements of the receptive field may be useful markers for the imbalances seen in patients with schizophrenia.
    Language English
    Publishing date 2023-10-21
    Publishing country United States
    Document type Preprint
    DOI 10.1101/2023.10.18.563001
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article ; Online: Sleep spindles in primates: Modeling the effects of distinct laminar thalamocortical connectivity in core, matrix, and reticular thalamic circuits.

    Yazdanbakhsh, Arash / Barbas, Helen / Zikopoulos, Basilis

    Network neuroscience (Cambridge, Mass.)

    2023  Volume 7, Issue 2, Page(s) 743–768

    Abstract: Sleep spindles are associated with the beginning of deep sleep and memory consolidation and are disrupted in schizophrenia and autism. In primates, distinct core and matrix thalamocortical (TC) circuits regulate sleep spindle activity through ... ...

    Abstract Sleep spindles are associated with the beginning of deep sleep and memory consolidation and are disrupted in schizophrenia and autism. In primates, distinct core and matrix thalamocortical (TC) circuits regulate sleep spindle activity through communications that are filtered by the inhibitory thalamic reticular nucleus (TRN); however, little is known about typical TC network interactions and the mechanisms that are disrupted in brain disorders. We developed a primate-specific, circuit-based TC computational model with distinct core and matrix loops that can simulate sleep spindles. We implemented novel multilevel cortical and thalamic mixing, and included local thalamic inhibitory interneurons, and direct layer 5 projections of variable density to TRN and thalamus to investigate the functional consequences of different ratios of core and matrix node connectivity contribution to spindle dynamics. Our simulations showed that spindle power in primates can be modulated based on the level of cortical feedback, thalamic inhibition, and engagement of model core versus matrix, with the latter having a greater role in spindle dynamics. The study of the distinct spatial and temporal dynamics of core-, matrix-, and mix-generated sleep spindles establishes a framework to study disruption of TC circuit balance underlying deficits in sleep and attentional gating seen in autism and schizophrenia.
    Language English
    Publishing date 2023-06-30
    Publishing country United States
    Document type Journal Article
    ISSN 2472-1751
    ISSN (online) 2472-1751
    DOI 10.1162/netn_a_00311
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Article: A neural model of modified excitation/inhibition and feedback levels in schizophrenia.

    Zhu, Jiating / Zikopoulos, Basilis / Yazdanbakhsh, Arash

    Frontiers in psychiatry

    2023  Volume 14, Page(s) 1199690

    Abstract: Introduction: The strength of certain visual illusions, including contrast-contrast and apparent motion, is weakened in individuals with schizophrenia. Such phenomena have been interpreted as the impaired integration of inhibitory and excitatory neural ... ...

    Abstract Introduction: The strength of certain visual illusions, including contrast-contrast and apparent motion, is weakened in individuals with schizophrenia. Such phenomena have been interpreted as the impaired integration of inhibitory and excitatory neural responses, and impaired top-down feedback mechanisms.
    Methods: To investigate whether and how these factors influence the perceived contrast-contrast and apparent motion illusions in individuals with schizophrenia, we propose a two-layer network, with top-down feedback from layer 2 to layer 1 that can model visual receptive fields (RFs) and their inhibitory and excitatory subfields.
    Results: Our neural model suggests that illusion perception changes in individuals with schizophrenia can be influenced by altered top-down mechanisms and the organization of the on-center off-surround receptive fields. Alteration of the RF inhibitory surround and/or the excitatory center can replicate the difference of illusion precepts between individuals with schizophrenia within certain clinical states and normal controls. The results show that the simulated top-down feedback modulation enlarges the difference of the model illusion representations, replicating the difference between the two groups.
    Discussion: We propose that the heterogeneity of visual and in general sensory processing in certain clinical states of schizophrenia can be largely explained by the degree of top-down feedback reduction, emphasizing the critical role of top-down feedback in illusion perception, and to a lesser extent on the imbalance of excitation/inhibition. Our neural model provides a mechanistic explanation for the modulated visual percepts of contrast-contrast and apparent motion in schizophrenia with findings that can explain a broad range of visual perceptual observations in previous studies. The two-layer motif of the current model provides a general framework that can be tailored to investigate subcortico-cortical (such as thalamocortical) and cortico-cortical networks, bridging neurobiological changes in schizophrenia and perceptual processing.
    Language English
    Publishing date 2023-08-15
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2564218-2
    ISSN 1664-0640
    ISSN 1664-0640
    DOI 10.3389/fpsyt.2023.1199690
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article: The inevitable inequality of cortical columns.

    Barbas, Helen / Zikopoulos, Basilis / John, Yohan J

    Frontiers in systems neuroscience

    2022  Volume 16, Page(s) 921468

    Abstract: The idea of columns as an organizing cortical unit emerged from physiologic studies in the sensory systems. Connectional studies and molecular markers pointed to widespread presence of modular label that necessitated revision of the classical concept of ... ...

    Abstract The idea of columns as an organizing cortical unit emerged from physiologic studies in the sensory systems. Connectional studies and molecular markers pointed to widespread presence of modular label that necessitated revision of the classical concept of columns. The general principle of cortical systematic variation in laminar structure is at the core of cortical organization. Systematic variation can be traced to the phylogenetically ancient limbic cortices, which have the simplest laminar structure, and continues through eulaminate cortices that show sequential elaboration of their six layers. Connections are governed by relational rules, whereby columns or modules with a vertical organization represent the feedforward mode of communication from earlier- to later processing cortices. Conversely, feedback connections are laminar-based and connect later- with earlier processing areas; both patterns are established in development. Based on studies in primates, the columnar/modular pattern of communication appears to be newer in evolution, while the broadly based laminar pattern represents an older system. The graded variation of cortices entails a rich variety of patterns of connections into modules, layers, and mixed arrangements as the laminar and modular patterns of communication intersect in the cortex. This framework suggests an ordered architecture poised to facilitate seamless recruitment of areas in behavior, in patterns that are affected in diseases of developmental origin.
    Language English
    Publishing date 2022-09-20
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2453005-0
    ISSN 1662-5137
    ISSN 1662-5137
    DOI 10.3389/fnsys.2022.921468
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article ; Online: Visual illusion susceptibility in autism: A neural model.

    Park, Sangwook / Zikopoulos, Basilis / Yazdanbakhsh, Arash

    The European journal of neuroscience

    2022  Volume 56, Issue 3, Page(s) 4246–4265

    Abstract: While atypical sensory perception is reported among individuals with autism spectrum disorder (ASD), the underlying neural mechanisms of autism that give rise to disruptions in sensory perception remain unclear. We developed a neural model with key ... ...

    Abstract While atypical sensory perception is reported among individuals with autism spectrum disorder (ASD), the underlying neural mechanisms of autism that give rise to disruptions in sensory perception remain unclear. We developed a neural model with key physiological, functional and neuroanatomical parameters to investigate mechanisms underlying the range of representations of visual illusions related to orientation perception in typically developed subjects compared to individuals with ASD. Our results showed that two theorized autistic traits, excitation/inhibition imbalance and weakening of top-down modulation, could be potential candidates for reduced susceptibility to some visual illusions. Parametric correlation between cortical suppression, balance of excitation/inhibition, feedback from higher visual areas on one hand and susceptibility to a class of visual illusions related to orientation perception on the other hand provide the opportunity to investigate the contribution and complex interactions of distinct sensory processing mechanisms in ASD. The novel approach used in this study can be used to link behavioural, functional and neuropathological studies; estimate and predict perceptual and cognitive heterogeneity in ASD; and form a basis for the development of novel diagnostics and therapeutics.
    MeSH term(s) Autism Spectrum Disorder ; Autistic Disorder ; Humans ; Illusions/physiology ; Visual Perception/physiology
    Language English
    Publishing date 2022-06-22
    Publishing country France
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 645180-9
    ISSN 1460-9568 ; 0953-816X
    ISSN (online) 1460-9568
    ISSN 0953-816X
    DOI 10.1111/ejn.15739
    Database MEDical Literature Analysis and Retrieval System OnLINE

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